Miscibility, intramolecular specific interactions and mechanical properties of a DGEBA based epoxy resin toughened with a sliding graft copolymer

The “sliding graft copolymer” (SGC), in which many linear poly-ɛ-caprolactone (PCL) side chains are bound to cyclodextrin rings of a polyrotaxane (PR), was prepared and employed to toughen diglycidyl ether of bisphenol A (DGEBA) based epoxy resin. The aim of the work is to understand the effect of SGC on the miscibility, morphology, thermal behavior, curing reaction and mechanical performance of the cured systems. From differential scanning calorimetry (DSC) analysis and dynamic mechanical thermal analysis (DMTA) of DGEBA/SGC thermosetting blends, it is found that DGEBA and SGC are miscible in the amorphous state. Fourier transform infrared spectroscopy (FTIR) suggested that the miscibility between SGC and DGEBA is due to the existence of intermolecular specific interactions (viz. hydrogen bonding). The impact strength is improved by 4 times for DGEBA/SGC (80/20) blends compared with that of the unmodified system. The increase in toughness of SGC-modified thermosets can be explained by the effect of intermolecular specific interactions of SGC with DGEBA, which is beneficial to induce the plastic deformation of matrix. This is the first report on utilizing this novel supramolecular polymer to toughen rigid epoxy matrix.